Stress-free deposition of [001] preferentially oriented titanium thin film by Kaufman ion-beam source

Abstract

We proposed a method to control and minimize residual stress in [001] preferentially oriented Ti thin films deposited by a Kaufman ion-beam source using a substrate temperature during deposition (T) as the parameter. We determined the residual stress, corresponding lattice parameters, and thickness of deposited films using X-ray diffraction and X-ray reflectivity measurements. We showed that the Ti film deposited at T≈273°C was stress-free with corresponding lattice parameters a0 and c0 of (2.954±0.003)Å and (4.695±0.001)Å, respectively. The stress-free sample has the superior crystallographic quality and pure [001] orientation. The Ti thin films were oriented with the c-axis parallel to the surface normal. We also investigated root mean square of surface roughness of deposited films by atomic force microscopy and it was in the range from ≈0.58nm to ≈0.71nm. Such smooth and stress-free layers are suitable for microelectromechanical systems.